Coin Case glitches

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Coin Case glitches are a variety of glitches involving the Coin Case in Gold and Silver Versions. They all involve listening to a Pokémon's cry then immediately using the Coin Case. Due to a translation bug, the Coin Case text is improperly terminated, making the game jump to $E112 every time it is used. This section of RAM is used by the game to store data related to Pokémon cries. Depending on the Pokémon's cry listened to, one of several effects will be activated: the game may restart with an altered color scheme and possibly blocks of color placed on the screen ("Glitch Dimension", "Shadow Puppet Effect" and "Shadow Puppets"), the game may freeze, or "Coin Case:" and a glitch phrase may be displayed (e.g., "which move?he PP of"). The most well known of these glitches can be performed in Pokémon Gold using the Machop in Vermilion City.

Display alterations

Glitch dimension

When accessed, the game restarts in what appears as an altered color scheme. This is particularly evident in the beginning cutscene/intro movie. The entire (apparently) game can be played as normal. When the player talks to a character, gets on his bike, goes through a door/portal, opens the menu, or does any other action affecting his sprite (though not necessarily changing it), a purple block is generated depending on the position of the player. At other times, seemingly randomly, blocks of color will be generated. For example, after flying to Cinnabar Island and Surfing downwards, the water will be blue, red and green in different places. Battles will be conducted with the colors of the HP bar, names, Pokémon, and Trainers altered, and with blocks of purple. Interestingly, the blocks seem to slide across the screen as the battle begins (at the point where the stat areas and Trainer slide into view). In towns, houses, routes, and other locations, blocks of color can be made to disappear by moving so that they move off-screen. The blocks appear to not be just a display problem, because they scroll with the map. This is apparently caused by the game thinking that it is being played on a Classic Game Boy.

When a cheating device is used to walk through objects, in some cases where the game does not freeze when the player walks out of the game, the game will restart in a "clean" glitch dimension where the background of the title screen is grey and has no blocky effects. Gameplay will be virtually the same, the only difference being; when a person is talked to, glitch dimension blocks will appear.

When the color scheme is altered in the title sequence to display Ho-Oh in color, this can only be done in Gold version. It will not work in Silver version and will not display Lugia in color.

Ho-Oh showing its true colors, in a "clean" Glitch Dimension.

Video

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Shadow Theater

Everything is completely white, except for the sprites (such as the player character, the NPCs, the Game Freak logo at the beginning). The sprites are either black, extremely darkened, dark blue, or near white. Sometimes an already-dark sprite will become white. Sprites with areas of high contrast (near black near white combinations) will appear partially black and partially white. Menus are not visible, but it is possible to navigate through them by memory. When viewing the PokéGear only the arrow selector pointing upwards is visible in the upper-left corner. During battles, the images of the Pokémon are not visible, but the blacked-out move graphics are. The specific cause of this is unknown, but is probably related to the cause of the Glitch Dimension.

Arbitrary code execution

Perfect EVs

When the game jumps to $E112, it starts executing data related to Pokémon cries as machine instructions. In particular, when Coin Case is used after hearing the Machop cry, the game will eventually reach address $E912. Data around that address is related to the overworld and can be manipulated through moving around in different patterns. When exiting Professor Elm's Laboratory and moving four steps to the right (prior to using the Coin Case after hearing the Machop's cry), the game will jump to address $FA98, which is in the middle of the data of the third Pokémon in the player's party. The game can therefore be made to execute specific code, based on the Pokémon's attributes such as species, item held, ..., by deliberately placing party Pokémon. By placing a specific species of Pokémon in the fourth slot of the party with the correct held item and first move, the game's execution may even be made to jump to the memory area that stores the items deposited in the player's PC, where code will execute based on the identifier and quantity of the items in the PC.

This video is not available on Bulbapedia; instead, you can watch the video on YouTube here.

Unused Memorygame

The glitch can be used for executing the code for the unused memorygame. The player needs a Quagsire, which holds the item HP-UP and a new captured Pokémon, which does not hold an item. Also the player needs the following items in his PC in the following order:

Max Revive x1

Full Restore x4

PP UP x56

X-Accuracy x99

Blackglasses x44

Dire Hit x44

Dire Hit x44

TM 16

Then the player has to go back to Professor Elm's Laboratory, save the game, exit and moving four steps to the right. If you now hear the cry of a Bellsprout, it is possible to enter the memorygame by opening the Coin Case.